1. Concept of temperature

2. Relation between different temperature scales

3. Absolute temperatures

4. Thermal expension

5. Specific heat

6. Change of state - latent heat

7. Heat transfer

Thermo $\equiv$ heat.

How much the temperature of the body changes when acceleration amount of heat is added or exhacted?

whether a charge of state occurs due to the application or the removal of heat?

Measurement of the temperature:

Thermometer

Mercury in glass

Scales:

1. Celcius scale

2. Fahrenheit scale

Measurement of the temperature: (ice point to a steam point )

Normal human body temperature = $98.6^{\circ} F$ = $37^{\circ} C$

100 division in the celcius scale.

180 division in the fahrenheit scale.

$\frac{180}{100} = \frac{9}{5}$

C = (F-32) $\times \frac{5}{9}$

$\frac{C}{5} = \frac{F-32}{9} \Rightarrow$ - $20^{\circ} C$

$\Rightarrow -\frac{20}{5} \times$ 9 = F -32

$\Rightarrow$ -36 = F - 32 = $-4^{\circ} F$

Kelvin scale has enormous scientific importance.

Absolute temperature: Below which no physical substance can exist or the lowest temperature in the Kelvin scale.

Conversion between the Celsius scale and the Kelvin temperature:

T = ($T_c$ + 273.15)K

T is the temperature in the Kelvin scale.

The change in temperature of the substance will be proportional to the pressure.

P $\propto$ T $\Rightarrow \frac{P}{T}$ = constant

The pressure is proportional to the height difference between the reference level and level of the manometer.

Temperature difference in the substance will be reflected in the height of the of mercury in the manometer with respect to the reference level.

Length, Area, volumne change with temperature.

$\Delta l \propto l_0$

$\Delta l \propto \Delta T$

$\Delta A=A_0 \alpha_A \Delta T$

$A=A_0+\Delta A=A_0+A_0 \alpha_A \Delta T =A_0(1+\alpha_A \Delta T)$

$l=l_0(1+\alpha_L \Delta T)$

A = $l^2$=${l_0}^2(1+\alpha_L \Delta T)^2$

• =${l_0}^2(1+2 \alpha_L \Delta T+\alpha_L^2 \Delta T^2)$ = ${l_0}^2 (1 + 2 \alpha_L \Delta T)$

$A=A_0(1+2 \alpha_L \Delta t)$

$\alpha_V$ for copper

$\alpha_V$: volume coefficient of the volume of expansion.

About 250 Kelvin it is linear and then it becomes non-linear.

What happens of holes?

Material expands and so the holes shrink.